Hydraulic brake



Feb. 6, 1940. a. F. cHARD. HYDRALC BRAKE Filed Dec. 28, 1955 Patented Feb. 6, 1940 UNITED STATES PATENT- OFFICE HYDRAULIC BRAKE Application December 28, 1935, Serial No. 56,414

14 Claims.

My invention relates to improvements in brakes.

My invention relates more particularly to hydraulic brakes.

As is well known to those familiar with brakes for automotive vehicles, it is frequently necessary to adjust the brakes. The brake bands wear under normal use and as a result a lesser braking effect is exerted by an identical manual applical tion. The usual method of correcting this is by shortening the effective brake rod length or increasing the leverage to actuate the brake shoes and bands. This is true of either mechanical or hydraulic brakes.

The principal object of my invention is to provide an improved hydraulic brake construction wherein the action of the same operates automatically to compensate for 4the wear on the brake bands and thereby vmakes each brake selfadjusting.

A further object of the invention is to provide an improved hydraulic brake having an.

automatic adjusting means for the brake shoes.

A further object is to provide an improved compensating valve member for this purpose.

A further object is to provide an improved hydrauic brake structure having a pair of compensating valve members capable of independent operation to automatically adjust the position of o each brake shoe with respect to the drum;

A-further objectis to provide an improved 'selfadjusting hydraulicbrake easily and cheaply constructed and capable Vof long and hard usewithout becoming brokenA prout of order.

Other objects andV advantages -will be more apparent tromthe following description wherein reference is had tothe accompanying sheet o! drawings upon which Fig'. 1 is a diagrammatic view of amaster cyl- I inder,` conduit and brake showing my improvedbrake cylinder construction, the parts being shown in the lrelease position;

Fig. 2 is a front elevational view of one of the flexible valves used;

4I Fig. 3 is a similar view of one of the valve cup members;

Fig. 4 is a cross-sectional view of a slightly modied form of cylinder the parts being shown in the expanded or applied position; andl 50 Fig. 5 is a longitudinal vertical section of the cylinder I4 showing the parts in'the expanded or applied position.

IIn the embodiment of my..invention which,I have chosen to illustrate the same, I have shown i lthe conventional type of hydraulic brake system,

(ci. iss- 152) including the master cylinder l0, which is n ormally located at a point accessible to the operation of an automotive vehicle and which is adapted to be connected by the iiuid conduits I2, with a plurality of brake cylinders I4, one of which is usually located at both of the front and back wheels of the automotive vehicle. The 'master cylinder I0 may be formed With a chamber I6, which. is in the form of an oil`reservoir and a cylinder portion I8 within which a piston mem- 10 ber is positioned. The piston member 20 may be of the usual type connected by a suitable rod construction 24, with a foot pedal or other manual operating means so that the same can be moved forward when it is desired to apply the 15 brakes of the vehicle. The piston may be formed with a cup-shaped leather or rubber seal member 22 at its forward end that normally engages a compression spring 25 positioned in cylinder I8 to return the piston 20 when pressure is released 20 on the lever 24. A suitable passageway 26 connects the cylinder I8 with the oil reservoir l5. The conduit i2 may extend` from the forward end of cylinder .I8 and be cenneeted'in a port 30 that enters a medial wall 32'inithe brake cylinder 25 I4. An axial bore 34 connects both o1 the chambers 36 and 3l with .the conduit l2. I provide a pair ofpiston Aseal members 40 positioned in the ychambers 36 and Il a spaced distance from the medial wall 32 of the cylinder. The piston seal 30A members v40 may be` constructed of rubber 0r other suitable material and are capable of move- .mentinwardly or mitwardly within the cylinder.

The piston sealsare positioned against the pistons 42 'by springs 41, The pistons 42 are mov- V35 ably mounted in the chambers )Band 38. v Each of thepistons 42 isj connected by the rods 13 to brake shoe 44 of the usual type provided with brake lining 46 upon the faces 43 of the shoes. The usual tension spring 50 connects the shoes; 40 44 to move them from contact with the drum 52' whenever the brakes are released. The brake' shoes 44 are pivotally mounted at their lower ends on suitable pin members 45. As thus far described, it is believed that the construction is known to those familiar in the art and that it is generally similar to certain well known hydraulic brakes which are in extensive use.

In order tocompensate for the wear on the brake linings 46 and to permit the brake shoes 50 to be removed from. contact with the brake drum only a specific distance, I'have provided a valve member 54 which is 'inserted inzthe chambers 36M and 38. The valvemember 54 may be a concave convex flexible disk preferably formed of rubber or other suitable materials and adapted to have its edge portion engage the sides 56 of the medial wall 42. It will be noted that the diameter of valve member 54 is less than the diameter of the chambers 36 and 38 so that 'the same may be flattened out within limits (Fig. 1). I further provide a pair of cup members which are held in place against the medial wall 32 by springr 4| and adapted to overlie and enclose the flexible valve members 54. The purpose thereof is to limit the' action of flexible valve 54. Each of the cup members 60 has a circular edge portion 62 and a plurality of openings 64 formed in thereof.

'Ihe operation of my improved valve is as follows:

When the brakes are applied (Figs. 4 and 5) by operation of the lever 24 to actuate the .piston 20 of the master cylinder, fluid under pressure is forced outwardly to port 3U and moves the flexible valves 54 away from the sides 56 of the wall 32, flows around said valves 54 through the openings 64 i'n the cup 60 and presses against the piston seals 40, thus operating to move outwardly the pistons 42 and through the connection with brake shoes 44, apply pressure against the drum 52. After the brakes are released (Fig. l), the forccof spring 50 Yvvill be suflicient to move the brake shoes 44 away from the drum 52 a short distance. This action will move the pistons 42 and piston seals 40 into the cylinder, tending to flatten out the iiexible valves 54 against the sides of medial wall 32. From the foregoing it can be seen that the valves 54 operate as check valves to prevent the return flow of fluid and thus permit the brake shoes 44 to be Withdrawn from the drum ,52 no greater than a desired distance, which is determined by the space S between the medial wall 32 and the concave wall of flexible valves 54. It will be apparent that no matter what the thickness of the brake shoe 46 is, the same will be withdrawn only sufficiently to provide the necessary clearance whenever the brakes are released. It is true even though one brake .c band may be considerably thicker than the other, 'aseach'of -the valves 54 operates independent of the other and serves only to control` the distance that the particular shoe with whichitis connect- A `construction wherein I"provide a' diaphragm member D-constructed of rubber or other suit- *f `-able material-'that is'held rigidlyat lits peripheral edgeand is capable of movementto flex inwardlyor outwardly t6 move the pistons 42. With ythis construction the device operates in a manf ner to that previously -described wherein the spring-member 42 is positioned against the piston seals 40. I

While I have illustrated and described only a A specific embodiment, it will be obvious to those made in the specific details shown and I do not Wish to be limited in any particular. Rather. what I desire. to secure and protect by Letters Patent ofthe United States is:

1. A`- brake cylinder for'hydraulic brakes having amedial wall and a cylindrical chamber on 'each side of said wall, a source of brake fluid connected to said medial wall, aperforated cup the wall 66 member positioned on each side of said wall, a spring retainer therefor, a piston seal, a flexible valve in each cup member adapted to permit uid to pass to operatesaid piston seal and a piston operable by said piston seal.

2. A brake cylinder for hydraulic brakes having a medial wall and a cylindrical chamber on each side of said wall,` a source of brake fluid connected to said cylinder at said wall, a perforated cup member secured on each side of said wall, a piston seal in each chamber, a flexible valve in each cup member, said flexible Valve adapted to permit fluid to pass into said chamber to move said piston seal, and a piston operable by said piston seal.

3. A brake cylinder for hydraulic brakes having a medial dividing wall therein and a cylindrical chamber on both sides of said wall, a passageway through said wall connecting said chambers, a source of brake fluid connected to said cylinders through said passageway, a perforated cup member positioned on each side of said wall, a piston seal in each chamber adjacent the open end thereof, a flexible convex concaveshaped valve positioned in each cup member, said fiexible valve adapted to permit fluid to pass into said chamber to move said piston seal outwardly, a piston slidably mounted in said chamber and movable by said piston seal, and a pair of pivoted brake shoe members connected to said pistons.

' 4. A brake cylinder for hydraulic brakes having a medial dividing wall therein and a cylindrical chamber on both sides of said wall,I a passageway through said wall connecting said chambers, a source of brake fluid connected to said cylinders through said passageway,l a perforated cup member placed on each side of said wall, a piston seal placed in each chamber adjacent the open end thereof, a fiexible convex concave-shaped' valve positioned in eachvcup ton slidablymounted in said chamber and movable by said piston -seal and a pair of pivoted brake shoemembersconnectedV to said pistons, said. valve adapted-.toiiatten after ay brakingpperation.

5. A. brakecylinder-fOr hydraulic bra-kes-vhaving `amedial Adividingzwall therein and .a cylindrical vchamber onrboth -sides of said wall, a passageway through said wall connecting saidchambers, a source of brake fluid connected to said Y cylinders throughsaid-v passageway, a perforated cupmember fastened on each side of said wall, a diaphragm rigidly` fixed in each chamber adjacent the open end thereof, a flexible convex shaped valve positioned infeach cup member overlying said passageway, said flexible valve adapted to permit fluid to pass into said chamber to move said 'diaphragm outwardly and to prevent the return of fluid, a piston slidably mounted in said chamber and movable by said diaphragm anda pair of pivoted brake shoe members connected to said pistons, said valve adapted to atten after a braking operation.

6. Hydraulic brake `mechanism embodying a chamber, a pistori'i'movable in the chamber, a Huid inlet to the chamber, a flexible valve controlling -said inlet,"said valve adapted to permit iiuid to pass into the chamber to move the piston outwardly and to prevent return of the fluid, said valve adapted to be flexed under the action of fluid pressure in the cylinder between the valve and piston to permit the pistonV to move inwardly a predetermined distance and while the said inlet is closed by said valve. 7. In a hydraulic braking system for automotive vehicles, a brake cylinder, a wall dividing said cylinder into 'a pair of chambers, a diaphragm rigidly mounted in each chamber adjacent the outer end thereof, a movable piston adjacent each diaphragm, a pair of pivoted brake shoe members associated with said diaphragms and a pair of flexible' valve members positioned adjacent said wall and adapted to permit fluid to flow outwardly against said diaphragms and capable of flattening when pressure is released to permit said brake shoes to be moved a determined distance from their advanced position.

8. In a hydraulic braking system for automotive vehicles, a brake cylinder, a wall dividing said cylinder into a pair of chambers, a passageway through said Wall, a diaphragm rigidly mounted in eachA chamber adjacent the outer end thereof, a movable piston adjacent each diaphragm, a pair of pivoted brake shoe members associated with said` diaphragms and a pair of flexible valve members positioned on opposite sides of said wall overlying said passageway and adapted to permit iiuid to flowioutwardly against said diaphragms and capable of flattening when pressure is released to permit said brake shoes to be moved a determined distance from their advanced position.

9. Hydraulic brake mechanism embodying a chamber, a piston at one end of the chamber. and a flexible valvel adjacent the other end of the chamber, said valve adapted to permit fluid to flow outwardly against said piston, and capable of flattening when pressure isreleased to permit said piston to be moved a determined distance from its advanced position, said valve being of a concave-convex disc formation.

10. Hydraulic brake mechanism embodying aV chamber, a piston at one end of' the chamber, a iiexible valve adjacent the other end of the chamber, said valve adapted to permit fluid to flow outwardly against said position, and capable of flattening when pressure is released to permit said piston to be moved a determined distance from its advanced position, said valve being ofv a concave-convex disc formation, and means for limiting the movement of the valve in the opening direction.

1 1. Braking mechanism embodying a cylinder having a fluid inlet opening, a piston in the cylinder, a flexible convex concavo shaped element positioned .to control said opening and movable under the influence of the fluid to permit an initial supply of fluid to enter the cylinder to move the piston in one direction, means for limiting such movement of 'said element, and means for moving the piston in the opposite direction, the last said movement of the piston operating to cause the said element to close the said inlet opening to trap the fluid in the cylinder, said element under predetermined conditions yielding under fluid pressure through said opening to admit fluid to the cylinder out of commingling relation with the fluid already in the cylinder, to augment the movement of the piston in the first said direction through the medium of the fluid trapped in the cylinder.

12. Braking mechanism embodying a cylinder having a uid inlet opening, a piston in the cylinder, a fiexible and floating diaphragm positioned to control said opening and movable under the influence of the fiuid to permit an initial supply of fluid to enter the cylinder to move the piston in one direction, means for limiting such' movement of said diaphragm, and means for moving the piston in the opposite direction, the last said movement of the piston operating to cause the diaphragm to close the said opening, said diaphragm under predetermined conditions yielding under fluid pressurethroughsaid opening to admit'uid to the cylinder, to' augment the movement of the piston in the first said direction through the medium of the said iiuid which is trapped in the cylinder, the said additional supply of iiuid being maintained out of comdirection, the last said movement of the' piston operating to cause the diaphragm to close the said opening, said diaphragm under predetermined conditions yielding under fluid pressure through said opening toadmit fluid tothe cylinder, to augment the movement of the piston in the first said directon through the medium of the said fluid already in the cylinder, the first recited said supply of fluid through said opening being maintained out of commingling relation with the fluid already in the cylinder.

14. Braking mechanism embodying a cylinder having an opening providing an inlet for the fluid, a piston in the cylinder, a Aexible floating element positioned to control said opening and movable under the influence of fluid pressure to permit the passage of fluid into the cylinder beyond the element to move said piston in one direction, means for limiting such movement of the said element, and means for moving the piston in the opposite direction, the last'said movement of the piston operating to cause the said element to engage an abutment to close said opening against the outlet of fluid from the cylinder, a portion of the said element being yieldable under predetermined conditions under the iniiuence of fiuid pressure through said opening, while the said element maintains the ,opening closed to the entrance of uid into the cylinder beyond the said element, the last said movement of the said element serving to augment the movement of the piston through the medium of the pressure of the fluid which is trapped in the cylinder beyond the said element.

GEORGE F. CHARD. 

